Carburetor



Feb. 11, 1964 H. A. BOLLER 3,120,841

CARBURETOR Filed Aug. 28, 1961 F i G. 4 a 38 hwma F I G. 3

INVENTOR.

HENRY A. BOLLER AGENT United States Patent 3,120,841 CARBURETGR Henry A. Boller, Orchard Lake, Mich., assignor to ACE Industries, Incorporated, New York, N.Y., a corporation of New Jersey Filed Aug. 28, 1%1, Ser. No. 134,171 Claims. (Cl. 123-119) This invention relates to carburetors for internal combustion engines and particularly to an automatic choke control device operable to control the mixture ratio of fuel to air during starting of an engine.

In conventional choke control devices, temperature responsive means and suction responsive means are provided to control the position of an unbalanced choke valve during starting of a cold engine. The temperature responsive means usually comprises a bimetallic coil spring which acts to yieldably resist opening of the choke valve until the spring is heated to a predetermined temperature by a stream of heated air from a manifold stove.

In a device of this type, the thermostat spring does not suificiently delay the opening of the choke valve since, when the engine is started during cold weather, the thermostat is often heated by the hot air from the manifold stove and permits full opening of the choke valve before the engine is heated to its normal operating temperature, thereby leaning out the fuel mixture and causing stalling of the engine. In restarting of a heated engine, the thermostat is often cooled to its cold starting position and causes too rich a fuel mixture to be supplied to the engine for easy starting.

It is, therefore, an object of the invention to provide an automatic choke control device adapted to delay opening of the choke valve during Warm up of a cold engine, and to delay closing of the choke valve upon stopping of a heated engine.

Another object of the invention is in a novel automatic choke control device, which more accurately reflects the true engine temperature.

The invention resides in the provision of an automatic control device in which the temperature of the thermostat is controlled by the temperature of water in the engine water jacket to thereby provide a control more truly dependent on engine temperature.

The invention embodies other novel features, details of construction and arrangement of parts which are hereinafter set forth in the specification and claims and illustrated in the accompanying drawings, forming part thereof, wherein:

FIGURE 1 is a side elevation showing an internal cornbustion engine provided with a carburetor choke device embodying features of the invent-ion.

'FlGURE 2 is an enlarged vertical section, partly in side elevation, showing the automatic choke device as applied to a carburetor to control the mixture ratio of fuel to air supplied to the engine.

FIGURE 3 is a fragmentary section taken along the line 33 of FIGURE 2.

FIGURE 4 is a section, corresponding to FIGURE 3, showing a modified form of the invention.

Referring now to the drawings for a better understanding of the invention and particularly to FIGURES 1 to 3 therein, a carburetor 2 is shown as mounted upon the intake manifold 3 of an internal combustion engine 4 3,120,841 Patented Feb. 11, 1964 "ice having a coolant jacket connected to a radiator 6 by conduits 7 and 8 to provide a closed circulation system through which fluid is continuously circulated by means of a pump 9 in the conduit 7 during operation of the engine.

The carburetor is shown as comprising an air horn section 11 securely mounted on a fuel bowl section 12. by means of cap screws 13. The fuel bowl section is secured to a throttle valve section 14 by cap screws 16, and the throttle valve section is secured to the intake manifold 3 by cap screws 17. A mixture conduit 18 extends downwardly through the air horn 11, bowl section 12, and throttle valve section 14 to deliver a mixture of fuel and air to the intake manifold.

A choke valve 19 is secured to a choke shaft 21 journaled at its ends in the air horn 11, The valve being unbalanced to open responsive to a downward flow of air through the mixture conduit 13. Venturis 22 are provided on the fuel bowl section 12 Within the mixture conduit, and a throttle valve 23 is secured on a throttle shaft 24 journaled in the throttle section 14.

The bowl section 12 comprises a constant level fuel bowl 26 which is supplied with fuel through an inlet 27 under control of a needle valve 23 actuated by a float 29. Fuel is supplied from the fuel bowl 26 to the mixture conduit 18 through a metering jet 1'5 to a main fuel passage 31 and through the main nozzle 24), as well as through the idle tube 25, the idle fuel passage 32 and out the idle ports 30 and 35.

A thermostatic housing 33 is provided with ears 34 formed with slots 36 to receive cap screws 37 for threaded engagement in the air horn 11, the housing having a slotted boss 38 (FIGURE 3) to engage the inner end of a spirally Wound bimetallic thermostatic spring 39 positioned within a chamber of the housing 33. The outer end of the thermostatic spring is disposed to engage and yieldably resist pivotal movement of a crank 41 secured to the choke shaft 21 by a cap screw 42. The air horn section 11 is formed with a cavity 40 and cylinder 43 opening into cavity 49 to receive a piston 44 which is connected to the crank 41 by a link 46.

An air passage 47 connects a point in the interior of air horn 1-1 to the interior of the cavity housing 40, and a suction passage 45 extends fro-m the lower end of the cylinder 43 to a portion 50 of the mixture conduit 18 posterior to the throttle valve 23. An insulating dielectric plate 55 separates cavity 40 from the interior of housing 33. An arcuate slot through plate 55 permits rotational movement of crank 41 with the choke shaft 21. The cylinder 43 is formed with the usual bypass 49 for the passage of air from cavity 40 past the piston 44 to the suction passage 45. In starting, and with piston 4-4 connected to the manifold 3, during cranking of the engine manifold vacuum will suck piston 44 downwardly, as viewed in FIGURE 2, to open the choke valve 19.

To provide an automatic choke control which more accurately reflects the true engine temperature, a water chamber 51 (FIGURE 3) is mounted on the thermostat housing 33 and connected to the coolant conduit 7 and engine coolant jacket by tubing 52 and 5.3, respectively. The water chamber has integral nipples 72 and 74 to which the tubing 52 and 53 may be attached, respectively. The housing 33 is formed with heat conducting fins 54 to conduct heat from liquid within the chamber 51 to the thermostat 39. The chamber 51 is mounted on the housing by means of a cap screw 56.

In the operation of the automatic choke control, thus shown and described, the choke valve 19 is biased toward its closed position by the thermostatic spring 39, when the engine is cold. Upon starting of a cold engine, the choke valve is moved toward its open position by the piston 44 and by air flowing down through the mixture conduit 18.

The coolant of the engine heats up slowly and when circulated through the water chamber 51 it prevents the thermostatic spring from heating up too rapidly, so that the resistance of the thermostat 39 to opening movement of the choke valve is retained a longer time than if the thermostat were heated by air passing through a stove on the exhaust manifold. The coolant heated choke prevents too rapid leaning out of the fuel mixture and stalling of the engine before the engine has reached an optimum operating temperature.

Restarting of a heated engine during hot weather, has

heretofore presented problems due to the fact that the thermostat cools off more rapidly than the engine and thereby acts to bias the choke valve to its closed position to provide a rich fuel mixture for the engine. Also in accordance with the invention, chamber 51 is positioned above the engine coolant jacket 7%, as shown in FIGURE 1, permits warm water in the jacket to pass upwardly into the water chamber '1 by convection. Thus, while standing after the engine has been heated up during a run, heated water from the jacket 79 will flow upwardly to keep the thermostat 39 heated and prevents it from closing the choke valve 1?. The heated engine is thus provided with a lean fuel mixture to facilitate starting and to prevent flooding of the engine.

FIGURE 4 illustrates a modified form of the invention with parts identical to those in the modification of FIGURE 3 having the same reference numbers. In FIGURE 4 the choke housing is formed with an annular water chamber 61 having inlet and outlet nozzles 76 and 78 for connection to the conduits 52 and 53, respectively.

While the invention has been shown in but two forms, it is obvious to those skilled in the art that it is not'so limited but is susceptible of various changes and modifications without departing from the invention or the scope of the depending claims.

i claim:

1. An internal combustion engine comprising an engine block, liquid cooling means for said engine, said means including a pump, a coolant jacket and a plurality of conduits connected to said coolant jacket and said pump for circulating coolant through said jacket, a carburetor mounted'on said block and having a portion thereof above said coolant jacket, said carburetor including a fuel and air mixture conduit therethrough and a choke valve movably mounted within said mixture conduit, said carburetor portion including a housing, a thermostatic spring withinsaid housing and oper-atively connected to said choke valve, said housing including a chaminer for said coolant adjacent to said thermostatic spring, and conduit .means connecting said chamber to two portions of said liquid cooling means at different levels below said housing chamber to provide circulation of coolant to said chamber by convection.

.2. An internal combustion engine comprising an en- .gine block, a liquid cooling circuit for said engine, said cooling circuit including a pump, acoolant jacket in contact with said engine block and a plurality of conduits connecting said coolant jacket to said pump for circulating coolant through said jacket, a carburetor mounted on said block and having a portion thereof above said cooling circuit, said carburetor including a fuel and air mixture conduit therethrough and a choke valve movably mounted within said mixture conduit, said carburetor portion including a housing, a thermostatic spring within said housing and 9 Bill/61y O Cttl to said choke valve,

said housing including a chamber for said coolant adjacent to said thermostatic spring, and a first conduit connecting said chamber to a portion of said coolant jacket below said housing chamber, and a second conduit connecting said chamber to said cooling circuit below said coolant jacket portion to provide circulation of coolant to said chamber by convection.

3. A carburetor for an internal combustion engine, said carburetor comprising a body having a fuel and air mixture passage therethrough, means on said body at one end of said passage for connecting said carburetor to the intake manifold of an engine, a choke valve shaft journaled in said body and extending transversely through the other end of said mixture passage, an unbalanced choke valve Within said other mixture passage end and fixed to said choke .shaft for rotational movement from an opened to a closed position, a choke lever fixed to one end of said choke valve shaft, said choke lever having an arm, a housing structure mounted on said body adjacent to said choke lever, said housing structure formed with a recess, a heat insulating wall between said body and said housing and forming a first chamber with said body enclosing said choke lever, said insulating wall closing said recess to form a substantially closed second chamber, said lever arm extending through said heat insulating wall into said second chamber, said housing structure formed with a third chamber, a heat conductive wall separating said second and third chambers, and a thermostatic coil spring within said second chamber and having one end fixed to the avail of said recess and the other end thereof operatively connected to said choke lever anm, said housing structure having an inlet pass-age to and an outlet passage from said third chamber adapted to be connected to a liquid engine cooling system.

4. A carburetor for an internal combustion engine, said carburetor comprising a body having a fuel and air mix ture passage therethrough, means on said body at one end of said passage for connecting said carburetor to the intake manifold of an engine, a choke valve shaft journaled in said body and extending transversely through the other end of said mixture passage, an unbalanced choke valve within said other mixture passage end and fixed to said choke shaft for rotational movement from an opened to a closed position, a choke lever fixed to one end of said choke valve shaft, said choke lever having an arm, a housing structure mounted on said body adjacent to said choke lever, said housing structure formed with a recess, a heat insulating wall between said body and said housing and forming a first chamber with said body enclosing said choke lever, said insulating Wall closing said recess to form a substantially closed second chamber, said lever arm extending through said heat insulating wall into said second chamber, said housing structure formed with a third chamber, a heat conductive wall separating said second and third chambers, and a thermostatic coil spr-ing within said second chamber and having one end fixed to said heat conduction Wall and the other end thereof operatively connected to said other choke lever arm, said housing structure having an inlet passage to and an outlet passage from said third chamber adapted to be .connected to a liquid engine cooling system.

5. A carburetor for an internal combustion engine, said carburetor comprising a body having a fuel and air mixture passage therethrough, means on said body at one end of said passage for connecting said carburetor to the intake manifold of an engine, a choke valve shaft journaled in said body and extending transversely through the other end of said mixture passage, an unbalanced choke valve within said other mixture passage end and fixed to said choke shaft for rotational movement from an opened to a closed position, a choke lever fixed to one end of said choke valve shaft, said body having a cylindrical recess and a vacuum passage connecting said recess to said one mixture pas-sage end, a piston movably mounted in said cylindrical recess, said choke lever having a pair of arms,

5 means operatively connecting said piston to one of said lever arms, a housing structure mounted on said body adjacent to said choke lever, said housing structure formed with a recess, a heat insulating wall between said body and said housing and forming a first chamber with said body enclosing said choke lever, said insulating wall closing said recess to form a substantially closed second chamber, the other of said lever arms extending through said heat insulating Wall into said second chamber, said housing structure formed with a third chamber, a heat 10 to said other choke lever arrn, said body formed with 15 6 air passage means connecting said first chamber to said other mixture passage end and to said vacuum passage, said housing structure having an inlet passage to and an outlet passage from said third chamber adapted to be 5 connected to a liquid engine cooling system.

References Cited in the file of this patent UNITED STATES PATENTS 1,598,677 Donning et al Sept. 7, 1926 1,754,028 Martin et al. Apr. 8, 1930 2,702,536 Carlson Feb. 22, 1955 2,992,641 Sarto July 18, 196 1 FOREIGN PATENTS 1,223,427 France Feb. 1, 1960 

1. AN INTERNAL COMBUSTION ENGINE COMPRISING AN ENGINE BLOCK, LIQUID COOLING MEANS FOR SAID ENGINE, SAID MEANS INCLUDING A PUMP, A COOLANT JACKET AND A PLURALITY OF CONDUITS CONNECTED TO SAID COOLANT JACKET AND SAID PUMP FOR CIRCULATING COOLANT THROUGH SAID JACKET, A CARBURETOR MOUNTED ON SAID BLOCK AND HAVING A PORTION THEREOF ABOVE SAID COOLANT JACKET, SAID CARBURETOR INCLUDING A FUEL AND AIR MIXTURE CONDUIT THERETHROUGH AND A CHOKE VALVE MOVABLY MOUNTED WITHIN SAID MIXTURE CONDUIT, SAID CARBURETOR PORTION INCLUDING A HOUSING, A THERMOSTATIC SPRING WITHIN SAID HOUSING AND OPERATIVELY CONNECTED TO SAID CHOKE VALVE, SAID HOUSING INCLUDING A CHAMBER FOR SAID COOLANT ADJACENT TO SAID THERMOSTATIC SPRING, AND CONDUIT MEANS CONNECTING SAID CHAMBER TO TWO PORTIONS OF SAID LIQUID COOLING MEANS AT DIFFERENT LEVELS BELOW SAID HOUSING CHAMBER TO PROVIDE CIRCULATION OF COOLANT TO SAID CHAMBER BY CONVECTION. 